Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
Proc Natl Acad Sci U S A. 2010 Mar 2;107(9):3982-7. doi: 10.1073/pnas.0911565107. Epub 2010 Feb 10.
Iron oxygenases generate elusive transient oxygen species to catalyze substrate oxygenation in a wide range of metabolic processes. Here we resolve the reaction sequence and structures of such intermediates for the archetypal non-heme Fe(II) and alpha-ketoglutarate-dependent dioxygenase TauD. Time-resolved Raman spectra of the initial species with (16)O(18)O oxygen unequivocally establish the Fe(IV) horizontal lineO structure. (1)H/(2)H substitution reveals direct interaction between the oxo group and the C1 proton of substrate taurine. Two new transient species were resolved following Fe(IV) horizontal lineO; one is assigned to the nu(FeO) mode of an Fe(III) horizontal line O(H) species, and a second is likely to arise from the vibration of a metal-coordinated oxygenated product, such as Fe(II) horizontal line O horizontal line C(1) or Fe(II) horizontal line OOCR. These results provide direct insight into the mechanism of substrate oxygenation and suggest an alternative to the hydroxyl radical rebinding paradigm.
铁氧还蛋白生成难以捉摸的瞬态氧物种，以在广泛的代谢过程中催化底物的氧化。在这里，我们解析了典型的非血红素 Fe(II)和α-酮戊二酸依赖性双加氧酶 TauD 中这些中间产物的反应序列和结构。与 (16)O(18)O 氧的初始物种的时间分辨拉曼光谱明确确立了 Fe(IV)水平线 O 结构。(1)H/(2)H 取代揭示了氧基团与底物牛磺酸的 C1 质子之间的直接相互作用。在 Fe(IV)水平线 O 之后解析出两个新的瞬态物种；一个被分配给 Fe(III)水平线 O(H)物种的 nu(FeO)模式，另一个可能源自金属配位的含氧产物的振动，例如 Fe(II)水平线 O 水平线 C(1)或 Fe(II)水平线 OOCR。这些结果提供了对底物氧化机制的直接洞察，并提出了替代羟基自由基再结合范例的可能性。
